Method of and apparatus for elevating devices in wells



J. C. STOKES Oct. 28, 1930.

METHOD OF AND, APPARATUS FOR ELEVATING DEVICES IN WELLS 7 Filed June 11, 1929 Patented Oct. 28, 1930 UNITED STATES JOHN G. STOKES, on

PA-TENT OFFICE HOUSTON, TEXAS, ASSIGNOR TO REED ROLLER BIT COMPANY, OF HOUSTON, TEXAS, A CORPORATION OF TEXAS vMETHOD OF AND APPARATUS FOR ELEVATING DEVICES IN WELLS Application filed June 11,

This invention relates to deep well drilling and more particularly to methods of and apparatus for elevating devices through drill stems. I

In deep well drilling, the removal of a long drill stem from a hole is a most diflicult and time consuming task. It being unnecessary, under normal conditions, to remove a drill stem except to change cutters and to remove cores, inventors have produced collapsible bits and core barrels removable upwardly through a drill stem while the drill stem remains in the hole,.and these are now in common use.

To'efiect the removal of collapsible bits and core barrels through the drill stem, overshots have been devised which are lowered in the drill stem by means of a cable.

While the use of an overshot, cable and associated apparatus has eliminated the great task of removing drill stems from holes; and they are capable of removing a collapsible bit or core barrel in much less time; the cable and apparatus associated therewith are costly and the use thereof consumes a considerable amount of time.

This invention has for its object the provision of a new and improved method of and apparatus for removing collapsible bits, core barrels and other devices from drill stems, while the drill stems are in the hole, without the use of cables or the like.

The accompanying drawings are illustrative of the preferred embodiment of the apparatus.

Fig. 1 is afragmentary sectional elevation of a drill stem having a removable core barrel and the overshot therein, the overshot being broken for the purpose of illustration; Fig. 2, a fragmentary vertical section of the upper end of the overshot within the drill stem; and Fig. 3, a fragmentary vertical section of the lower end of the overshot and of the removable core barrel, both within the drill stem.

While I have illustrated a drill stem and a removable, core barrel with which my overshot will be found particularly useful, it is to be understood at the outset that the overshot may be used in any other drill stem to 1929. Serial No. 369,990.

elevate any device. And my method may be used by means of quite dissimilar apparatus, all within the scope of the hereinafter appearing claims.

The drill stem disclosed by the drawing is indicated at 1, and has mountedon its ment of the core barrel by the core entering thereinto. And the conical head 2 of the barrel extends into the coupling.

The internal diameter'of the coupling 3 is considerably less than that of the drill stem 1, as indicated at 3, and the upper internal shoulder of said coupling is inclined downwardly and inwardly, as indicated at 3", for the guidance of the overshot 5. The coupling is also provided with longitudinal slush ducts 3.

When the overshot 5 moves downwardly, it is guided into the portion 3" of the coupling by the internal shoulder 3 and engaging the head 2 of the core barrel centers the same so that the shoulder 4* is moved from beneath the shoulder 3 and the core barrel may be moved upwardly through the coupling. Meanwhile, the spring fingers 5 of the overshot engage said head so that when the overshotmoves upwardly it carries the core barrel with. it.

To keep the cutters of the bit cool and to remove the cuttings, drilling equipment invariably includes means to pump slush, that is, muddy water, down through the drill stem. f

This invention provides a buoyant overshot adapted to be forced downwardly by the slush pumped through the drill stem, to engage the core barrel or the like, and to rapidly pull the same upwardly to the top pressure on the slush 'comes necessary to remove the collapsible bit,

core barrel, or the like, upwardly through the drill stem, the buoyant overshot must be forced downwardly into engagement with the same, because the drill stem will normally be filled with slush. The overshot is, therefore, placed in the upper end of the drill stem and the pump operated to force slush into the drill stem. The slush, rushing downwardly in the drill stem, Will carry the overshot with it until the overshot moves into the coupling 3 and engages the conical head 2' of the core barrel. It may here be remarked that the overshot will then obstruct the passage of slush through the central opening 3 of the coupling, and consequently great pressure will be applied to the overshot to insure the engagement of the head 2 by the spring fingers 5*. A limited amount of slush will continue to pass through the longitudinal ducts 3 of the coupling this because it is believed advisable to at all times permit the passage of at least a small amount of slush through the drill stem. The

obstruction to the passage of slush by the overshot will be indicated by the increased load on the pump, whereby the driller may ascertain when the overshot has reached and engaged the core barrel.

Now when the pump is stopped, the slush is no longer forced through the drill stem and it, therefore, becomes a practically stationary body of water in-the drill stem. The overshot, being buoyant, will then rush upwardly in the slush to the top ofthe drill stem, pulling the core barrel with it. The consequent removal of the overshot and core barrel attached thereto from the top of the drill stem may quickly and easily be accomplished. Should the drill stem be dry, the overshot may, of course, be dropped down into the drill stem in which event it will fall into engagement with the core barrel) and the drill stem may then be filled with water in which the buoyant overshot will rise bringing the core barrel with it.

Uses of the invention in well casings and a other deep well apparatus, and with fluids other than water, all within the scope of the following claims, will occur to those skilled in the art.

through, and means to force a fluid through said drill stem, of an overshot movable in said drill stem, buoyant in said fluid, and adapted to engage said device. I

2. The combination with a drill stem, a device carried thereby and removable therethrough, and means to force a fluid throu h said drill stem, of an overshot movable 111 said drill stem, buoyant in said fluid, and adapted to engage said device, said stem having a reduced opening adjacent said device, the passage of fluid through said opening being obstructed by said overshot when said overshot engages said device.

3. The combination with a drill stem, a device carried thereby and removable therethrough, and means to force a fluid through said drill stem, of an overshot. movable in said stem, buoyant in said fluid, and adapted to engage said device, said stem having a reduced opening adjacent said device, and

ducts adjacent said opening, the passage of fluid through said opening being obstructed by said overshot when said overshot engages said device. J

4. The method of removing a device from a well consisting in connecting to said device an overshot buoyant in a fluid, and then filling said well with said fluid.

5. The method of removing a device from a drill stem consisting in placing in the stem an overshot adapted to engage said device and buoyant in a fluid, pumping said fluid into" said stem to force the overshot into engagement with said device, and then permitting the overshot and deviceconnected thereto to rise in said fluid. r

In testimony whereof, I hereunto affix my 

